Air valve type carburetor

Abstract

An air valve type carburetor of the kind in which a throttle valve is disposed in the downstream portion of a barrel interconnected to an engine via an intake manifold; a main nozzle is disposed upstream of the barrel and is connected to a jet of a float chamber; an air horn disposed on the barrel is connected to an air cleaner via an air connector; an air valve is disposed at the upper part of the main nozzle, faces at its tip the nozzle and is connected to the base end of a metering needle which is inserted into a through-hole of the air horn for free vertical movement therein; and a shield plate is fixed to the shank of the metering needle so as to prevent pressure pulsations inside the air connector from entering the through-hole and being applied to the surface of the fuel.

What is claimed is: 
     
       1. In an air valve type carburetor of the kind in which a barrel provided with a throttle valve has a main nozzle interacting with a jet disposed inside the float chamber of a fuel bowl and an air valve positioned in an air horn at the upper part of said barrel is interconnected by a link to the upper end of a metering needle inserted into a through-hole of said air horn for free vertical movement therein and facing said jet at the lower end of the needle, said through-hole having access to an air cleaner through an air connector, the improvement wherein a shield plate is rigidly fixed to the shank of said metering needle at a position in said fuel bowl proximate said through-hole when said air valve is fully open. 
     
     
       2. The air valve type carburetor of claim 1 wherein said shield plate is made of light-weight material for creating little side displacement of said metering needle when the needle moves up and down. 
     
     
       3. The air valve type carburetor of claim 2 wherein said light-weight material is foamed styrol. 
     
     
       4. The air valve type carburetor as defined in claim 1 wherein said shield plate is tapered with respect to said through-hole. 
     
     
       5. The air valve type carburetor of claim 4 wherein the tapered portion of said shield plate is concavely arcuate. 
     
     
       6. The air valve type carburetor of claim 4 wherein said shield plate is disc-shaped. 
     
     
       7. The air valve type carburetor of claim 4 wherein said shield plate is made of light-weight material for creating little side displacement of said metering needle when the needle moves up and down. 
     
     
       8. The air valve type carburetor of claim 7 wherein said light-weight material is foamed styrol.